Quick detachable arc chute assembly for contactors



Jan. 10, 1961 R. L. CARVER 2,967,921

QUICK DETACHABLE ARC CHUTE ASSEMBLY FOR CONTACTORS Filed Aug. 12, 1959 llllllllllllllllm I 23 FIG.4.

INVENTOR Robert L. Carver ATTORNEY United States Patent QUICK DETACHABLE ARC CHUTE ASSEMBLY FOR CONTACTORS Robert L. Carver, Prestonsburg, Ky., assignor to Ensign Electric & Manufacturing Co., Huntington, W. Va., a corporation of West Virginia Filed Aug. 12, 1959, Ser. No. 833,277

6 Claims. (Cl. 200-144) This invention relates to electric circuit makers and breakers, and more particularly to electromagnetically operated switches commonly known as contactors, and used to control the supply of current to large motors.

One well known type of contactor comprises a movable contact tip arranged to engage a fixed contact, usually associated with a magnetic blow-out coil. To confine and enclose the are which is produced at such contacts when the circuit is broken, it is conventional practice to provide what is known as an arc chute, comprising a pair of spaced, parallel plates of insulating material between which the fixed contact is mounted. The movable contact tip is also housed between these plates, so that, when it is desired to inspect or renew these tips, as is often the case, due to excessive wear or burning, it is necessary to remove the entire arc chute assembly.

These are chute assemblies, as heretofore constructed, have been secured to the frame of the contactor by means of a pair of bolts or screws, and, since a series of contactors is frequently mounted on a panel in close proximity to each other, these bolts or screws are relatively inaccessible and there is very little space in which to operate a wrench. The removal of an arc chute assembly from a contactor on such a panel has therefore been a difiicult and tedious operation.

The general object of the present invention is, there fore, to obviate the necessity for the use of bolts or screws, and to devise quick-detachable means, readily accessible from the front, for securing the arc chute assembly to the frame of the contactor.

A further object is to provide quick-detachable means of this character which can be operated without the use of tools of any kind.

Yet another object of the invention is to devise quickdetachable securing means which is of simple, inexpensive construction, and which will add very little to the cost of the contactor.

In order that the invention may be readily understood, reference is had to the accompanying drawings, forming part of this specification, and in which:

Fig. 1 is a side elevation of a contactor embodying the invention;

Fig. 2 is an end elevation thereof;

Fig. 3 is a fragmentary side elevation similar to Fig. 1, but showing the quick-detachable securing means in released position;

Fig. 4 is a similar view but showing the arc chute assembly as detached from the frame;

Fig. 5 is a side elevation of the arc chute assembly alone, with the quick-detachable securing means carried thereby; and

Fig. 6 is an end elevation of the arc chute assembly, looking toward the left hand side of Fig. 5, parts being omitted for simplicity.

Referring to the drawings in detail, the contactor illustrated is of a well-known type and comprises a frame made up of a vertically disposed casting 1 rigidly secured to a horizontal top plate or support member 2. An op- 2,967,921 Patented Jan. 10, 1961 crating magnet 3 is supported by the top plate or support member, and an armature 4, associated therewith, is pivoted to the casting 1 at 5, and carries a movable contact tip 6.

A fixed contact 7, of any suitable shape, is arranged to co-operate with the movable contact 6 and is mounted in the usual arc chute assembly. This comprises a pair of spaced, parallel plates 8 and 9 of insulating, arc-resisting material, having between their upper ends a metal block 10, connected with the fixed contact 7. The parts are fastened together by bolts 11, and a terminal 12 is mounted at the top of the assembly and connected with the fixed contact 7. The other terminal 12' is mounted on the top plate 2 and connected with the movable contact 6 by means of the usual braided flexible conductor 12*. It is common practice to mount a blowout coil (not shown) in the arc chute assembly, and it will be seen that the movable contact 6 extends into a chamber, just below the fixed contact 7 (see Fig. 6) which encloses both contacts. Consequently, in order to get at these contacts, especially the movable contact 6, for inspection or repair, it is necessary to remove the entire arc chute assembly from the frame.

In order to insulate the arc chute assembly and terminal 12 from the frame, the end of the top plate or support member 2 is sandwiched between top and bottom insulating members 13 and 14, having at their end a cylindrical boss 15, and a lug 16 is formed on the lower member 14 which co-operates with a projection on the plate 10 to aid in properly positioning the arc chute assembly with respect to the frame.

The construction so far described constitutes the conventional, standard arrangement commonly employed, and forms no part of the present invention. In this standard, conventional arrangement, however, the arc chute assembly was secured to the frame by a pair of bolts (not shown), which passed down through holes in the insulating members, one of such holes passing through the boss 15 and engaged in threaded openings in the metal plate 10, the position of one such opening being indicated at 17 in Fig. 4, and the other opening not being shown. These were the bolts which were, in practice, so difficult to remove, because of the fact that the contactors are usually mounted close together on a control panel, and there is no room in which to swing a wrench.

In my improved construction, I do away with these bolts. In place of one of them, however, namely the one which passed through the boss 15, I provide a special bolt 18, having near its lower end a collar or radial flange 19, which bears against the under side of the insulating member 14. The upper end of the bolt 18 is threaded, as indicated at 20, and on this threaded end works a nut 21. It will be obvious that by tightening this nut the upper and lower insulating members 13 and 14 can be drawn together and caused to grip the top plate between them. It will also be understood that this nut, once having been screwed down, does not have to be disturbed when it is desired to remove the arc chute assembly.

Projecting down from the lower end of the bolt 18, below the shoulder 19, is a smooth pin 22, adapted to enter the hole 17 in the metal plate 10, and thus 1aterally position the arc chute assembly with respect to the frame. While this guide pin is smooth, and the opening 17 may have a smooth bore to receive it, the threaded openings such as 17, found in existing models now in use, may be utilized to receive the pin 22. In this way, my quick-detachable securing means can be applied to existing types of contactors without the necessity of boring any additional holes in the arc chute assembly or in the frame of such contactors. The only thing necessary to do to the frame is to discard the original pair of bolts or screws and substitute a single special bolt such as 18.

My improved, quick-detachable securing means itself includes a clamping lever 25, comprising a pair of side arms, preferably made of non-magnetic material, and a cross bar 26, thus forming a U-shaped structure. The free ends of the arms are pivoted at 24 to the arc chute assembly. It is the usual practice to mount iron plates 23 on the insulating plates 8 and 9, to assist in forming a magnetic circuit for the blow out coil, and I find it convenient to pivot the lever on these iron plates. A U- shaped bail 28 has its ends pivoted to the lever 25 at 27, a short distance from the pivots 2- This bail is of such size and shape as to embrace the arc chute assembly and the insulating members 13 and 14, forming part of the frame. The upper surface of the top insulating member 13 has a transverse notch 29 formed therein, and the bend of the bail 28 engages and fits in this notch, as shown in Fig. l. The cross bar 26 acts as a stop to limit the swinging movement of the lever 25 about its pivot 24, and when in this limiting position, it will be seen that the pivots 27 of the bail 28 lie directly below and slightly to one side of the pivot 24. This supports the arc chute assembly and holds it in normal operative position.

When it is desired to release and remove the arc chute assembly, all that is necessary is to swing the lever 25 up in a counter-clockwise direction, as indicated by the arrows in Fig. 3, and then shift the bail 28 from the dotted line to the full line position in a clockwise direction, also as indicated by the arrows in Fig. 3. This leaves the arc chute assembly entirely free, so that it can be readily detached from the frame, as shown in Fig. 4, the interlocking parts 17-22 being easily separable by a downward movement.

To replace the arc chute assembly, it is simply put into normal position, in contact with the insulators 13, 14, and the bail 2S swung over and engaged with the notch 29, as shown in dotted lines in Fig. 3, and the lever 25 swung downwardly into the position shown in Fig. 1 and also in dotted lines in Fig. 3.

it will be understood that the bail is somewhat resilient. As shown, this is accomplished by making the bend or cross-bar resilient, so that, when in normal position, it is slightly bowed as illustrated in Fig. 2. Another expedient would be to make the cross-bar rigid, and the side arms resiliently extensible, as by helical springs. In either case, when in normal position, as shown in Fig. l, the bail is under tension.

It will further be noted that, as the lever 25 is swung down from the position shown in full lines to that indicated by dotted lines in Fig. 3, the pivot 27 of the bail moves across the line extending from the pivot 24 to the point 29 at which the bend of the bail engages the top insulating member, and, owing to the resilience of the bail, it is securely held and locked in this position.

What I claim is:

1. In a contactor having a frame including a horizontal support member, and an arc chute assembly disposed beneath said support member so that the top of said arc chute assembly lies adjacent the bottom of said support member, and means for detachably securing said arc chute assembly to said frame in such manner that said are chute assembly depends from said support member, said means comprising a clamping lever pivotally mounted at one end on said arc chute assembly, and a U-shaped bail embracing said support member and said are chute assembly and pivoted at its ends to said clamping lever.

2. In a contactor having a frame including a horizontal top support member rigidly connected with a vertically disposed casting, a movable contact pivotally mounted on said casting, a fixed contact cooperating with said movable contact, and an arc chute assembly disposed beneath said top support member and enclosing both of said con tacts, and means for detachably securing said are chute assembly to said support member in such manner that said arc chute assembly depends from said support member, said means comprising a clamping lever pivotally mounted at one end on said arc chute assembly, and a U-shaped bail embracing said top support member and said are chute assembly and pivoted at its end to said clamping lever, said frame and said are chute assembly having longitudinally separable interlocking parts for laterally positioning said are chute assembly with respect to said frame.

3. In a contactor having a frame comprising a horizontal top plate rigidly connected with a vertically disposed casting, a movable contact pivotally mounted on said casting, a fixed contact co-operating with said movable contact, and an arc chute assembly disposed beneath said top plate and enclosing both contacts, quick-detachable means for securing said are chute assembly to said top plate comprising supporting means carried by said top plate, a clamping lever pivotally mounted at one end on said are chute assembly, and a U-shaped bail embracing said supporting means and arc chute assembly and pivoted at its ends to said clamping lever, said supporting means and are chute assembly having downwardly separable in terlocking means for laterally positioning said arc chute assembly with respect to said supporting means.

4. In a contactor comprising a frame including a horizontally disposed top plate interposed at its end between top and bottom insulating members, a movable contact pivotally mounted on said frame, a fixed contact co-operating with said movable contact, and an arc chute assemly disposed beneath said top plate and said insulating members and enclosing both of said contacts, means for detachably securing said arc chute assembly to said frame so that said are chute assembly depends from said top plate, said means comprising a clamping lever pivotally mounted at one end on said are chute assembly, and a U-shaped bail embracing said are chute assembly and said insulating members and adapted to engage said top insulating member, said bail being pivoted at its ends to said clamping lever, a bolt passing vertically through said insulating members for causing them to grip said top plate between them, and a smooth pin projecting downwardly from the lower end of said bolt, said are chute assembly having a socket to receive said smooth pin.

5. In a contactor having a frame including a horizontal support member interposed at its end between upper and lower insulating members, a movable contact pivotally mounted on said frame, a fixed contact co-operating with said movable contact, and an arc chute assembly disposed beneath said support member so that the top of said are chute assembly abuts the bottom of said lower insulating member, means for detachably securing said are chute assembly to said frame in such manner that said are chute assembly depends from said support member, said means comprising a clamping lever pivotally mounted at one end on said are chute assembly, and a resilient U-shaped bail embracing said arc chute assembly and frame, the bend of said bail being constructed to engage said frame, and the ends of said bail being pivoted to said clamping lever, the pivots of said lever and hail being so positioned that, as said lever is swung on its pivot, said bail is placed under tension, and, as the swinging movement continues, and approaches its limit, the pivots of said bail move across the line joining the pivot of said lever with the point at which the bend of said bail engages said frame, whereby said bail is locked.

6. In a contactor comprising a frame including a horizontally disposed top plate interposed at its end between top and bottom insulating members, a movable contact pivotally mounted on said frame, a fixed contact co-operating with said movable contact, and an arc chute assembly enclosing both contacts, quick-detachable means for securing said are chute assembly to said top plate whereby said are chute assembly extends downwardly therefrom, said means comprising a clamping lever pivotally mounted at one end on said are chute assembly 2,967,921 5 for limited swinging movement, and a resilient U-shaped ing the pivot of said lever with the point at which the bail embracing said are chute assembly and insulating bend of said bail engages said top insulating member,

members, the bend of said bail being constructed to enwhereby said bail is locked.

gage said top insulating member, and the ends of said References Cited in the file of this patent bail being pivoted to said clamping lever, the pivots of 5 said lever and hail being so positioned that, as said lever UNITED STATES PATENTS is swung on its pivot, said bail is placed under tension, and 699,002 Nugent a- Apr. 29, 1902 as the swinging movement continues and approaches its 1,997,772 Graves Apr. 16, 1935 limit, the pivots of said bail move across the line connect- 2,724,094 Lewis Nov. 15, 1955 

